Every day, tens of millions of barrels of oil are transported over bodies of water which are also important sources of food and drinking water to millions of people. Oil spills, of course, have a tremendous negative impact on marine life, potable water, and create a “ripple effect” in, e.g., the tourist industry, health care in affected areas, etc. As the world's demand for crude oil continues to grow, the need to have effective remedies available to address oil spills quickly, and effectively does as well.
Plant based materials are well known as oil adsorbing materials. Their efficacy, however, is hindered when the oil material to be adsorbed is combined with water. The chemical composition of plant materials is such that they are hydrophilic, and will adsorb water more readily than petroleum products. Further, when these plant materials adsorb water, they become heavy and sink.
There have been attempts made to use plant materials to remove oil spills. For example, see Banerjee, et al., Chemosphere, 64:1026-1031 (2006); Sayed, et al., Desalination, 194:90-100 (2006); Annunciado, et al., Marine Pollution Bulletin, 50:1340-1346 (2005); Karakasi, et al., Fuel, 89:3966-3970 (2010); and Carmody, et al., J. Colloid and Interface Sci., 305:17-24 (2007). Annunciado and Banerjee are the most relevant of these, as they deal with plant materials for oil adsorption. U.S. Pat. No. 4,444,148 to Lander teaches coating plant materials with paraffin, to render them buoyant and hydrophobic. The invention disclosed herein, however, differs markedly from what is disclosed in the prior art. In the case of Banerjee et al., fatty acids are grafted onto plant materials, using H2SO4 as the catalyst, whereas the invention, as will be seen herein, involves physical coating without the use of a grafting catalyst. Further, the preferred coating materials of Banerjee et al., are low molecular weight lipids which are liquid at room temperature, as compared to the preferred materials of the invention, which are animal fats and solid at room temperature. Also, Banerjee et al. state that particles of 227 μm were the optimal size for oil adsorption. Experience has shown, however, that particles of this small size are not buoyant, and thus are not useful for removal of oil from bodies of water. Also, Annunciado states that smaller particles adsorb oil at a much lower rate than do the particles of the invention.
There have been various additional approaches to the problem of removing hydrocarbon spilled as a result of various actions. U.S. Pat. No. 5,492,881 to Diamond describes various products which can be used to absorb hydrocarbon, such as oil. Cellulose materials are treated to render products hydrophobic and oleophilic. Options include the incorporation of microbes, a fire retardant, low ash content (1%), and incorporation of paraffin. Removal of spilled petroleum products using bacteria is an inherently slow process because of the biological reaction. Such is not a feature of the present invention. U.S. Pat. No. 4,072,794 to Tomita et al. coats fibers with paraffin, and also includes latex in the composition. Latex is not biodegradable, in contrast to the invention described herein.
International application WO 2012/136981 converts plant materials to charcoal, with dimineralizing. Hence, natural, untreated plant materials are not used.
U.S. Pat. No. 4,172,039 to Akiyama describes use of coir dust, i.e., material from coconut fruit. Coir dust has different porosity from the materials of the invention. The difference in composition requires the use of a containment means in using the coir based product, in contrast to the invention described herein.
WO 1998/45018 describes a product based upon coconut palms, where no hydrophobic coating is utilized.
None of these references teach or suggest the invention described herein and elaborated upon in the disclosure which follows.